Qatar Investment Authority has agreed to buy a 43-storey office building in Singapore from BlackRock for S$3.4 billion ($2.5 billion).

The Gulf emirate's sovereign wealth fund, which has been on a high-profile buying spree in world capitals, reached the deal to buy Asia Square Tower 1 located along Marina View at Marina Bay.

As per the deal, the Qatari fund buys more than 1.25 million square feet of net lettable area in Singapore, BlackRock and Qatar Investment Authority said in a joint statement.

It is the largest-ever single-tower real estate deal in the Asia-Pacific region, Reuters quoted sources as saying.

"Following this flagship transaction, we expect there will be increasing investor interest in Singapore prime office stock in the coming months," Greg Hyland, head of capital markets Singapore at JLL, said in a statement. JLL and CBRE advised BlackRock in the sale.

The Qatar Investment Authority is paying $1,960 per square foot for the property which houses Google and Citgroup, the Financial Times reported.

"I have a feeling we might look back at this point and say 'that marks the recovery point' for the market... We have dry powder in new funds that we've raised and we're actively looking at new properties in Singapore," John Saunders, head of Asia Pacific for BlackRock Real Estate, said.